The existence of a new Chinese 6 × 6 armoured personnel carrier was first revealed in early 1986 and one of the 16 prototype vehicles made its first public appearance during an exhibition that took place in Beijing in November 1986.

At that time it was confirmed that the vehicle had been designed and built by the NORINCO (China North Industries Corporation) Vehicle Research Institute outside Beijing which had also built the prototype vehicles.

Using automotive components of the 6 × 6 WZ 551, NORINCO has also developed 4 × 4 and 8 × 8 versions with the former having been built in production quantities for the NORINCO Red Arrow 8 ATGW systems covered later in this entry.

This family of vehicles is capable of being used for a wide range of roles, including 82 mm and 120 mm mortar carriers, and be armed with a wide range of weapons including 12.7 mm machine gun, 25 mm cannon, 90 mm or 105 mm guns.

In May 2005 it was stated that the Royal Thai Army was to take delivery of 97 WZ 551 or WMZ 551 series (6 × 6) APCs for use by the 2nd Army Region in northeast Thailand, with a small number also being supplied to the police.

Recent information has confirmed that Nepal has taken delivery of an undisclosed quantity of WZ 551 APC armed with a roof-mounted 12.7 mm MG. Description

There are minor differences between prototype WZ 551 vehicles and the following description should be taken as provisional.

Although the 6 × 6 version of the WZ 551 is very similar in appearance to the now Renault Trucks Defense VAB (6 × 6) vehicle, it has a number of important differences as well as being longer, wider and heavier.

The hull of the WZ 551 is of all-welded steel construction, protecting the crew from small arms fire and shell splinters.

The driver sits at the front on the left with the vehicle commander to his right and the 12.7 mm machine gunner to his rear. Their compartment is separated from the troop compartment by an airtight door.

The commander and driver each have a windscreen to the front that is covered, when in a combat area, by an armoured shutter hinged at the top. When these are lowered, forward observation for each is via three roof-mounted day periscopes, the centre one of which can be quickly replaced by a passive night vision device.

Both the commander and driver have a rear-opening circular roof hatch.

On at least one of the prototypes there is a door in the lower half of the hull between the first and second road wheels. This is for maintenance purposes.

The engine compartment is to the rear of the driver's compartment and separated from the remainder of the vehicle by airtight bulkheads. The air inlet and outlet louvres are in the roof of the engine compartment with the exhaust pipe running along the upper left side of the hull.

The air-cooled diesel engine is coupled to a fully automatic transmission with five forward gears and one reverse, with torque converter. Axles have double reduction and differential locking.

The troop compartment is at the rear of the hull and the troops enter via a large door that is hinged on the right and has a firing port and a vision block. The infantry sits on bench-type seats down either side of the hull facing each other. However, on the 25 mm version the troop seating layout is different.

Over the top of the troop compartment are four oblong roof hatches, two either side, that are hinged on the outside and can be locked vertical if required.

In each side of the troop compartment are four firing ports with a day periscope mounted above in the roof of the vehicle. The first firing port in each side is for a 7.62 mm machine gun, with the remaining three being for assault rifles. Each firing port has a gas extractor device. The diesel fuel tanks are located one either side of the troop compartment.

The WZ 551 is fully amphibious, propelled in the water by two shrouded propellers mounted one either side under the rear of the vehicle. These are swung backwards through 180° for improved propulsion when in the water. Before entering the water, a trim vane is erected at the front of the vehicle and the bilge pumps, located in the floor at the rear, are switched on.

Standard equipment includes an NBC system, night vision equipment for the driver, an automatic fire extinguishing system and run-flat tyres. If the tyres are punctured by bullets or splinters it can still travel a distance of 100 km at a speed of 40 km/h. Variants

The basic WZ 551 is also referred to as the Type 90 and the first versions were powered by a KHD F8L413F diesel developing 256 hp.

The police and military police use respectively the WZ 901 and the WZ 551WJ, also known as the ZSL-90WJ.

This is a cargo model with a payload of 7 tonnes.

NORINCO is developing a new highly mobile Air-Defence System (ADS) called Yitian, based on the WZ 551 6 × 6 armoured personnel carrier chassis.

Mounted on the upper part of the WZ 551 chassis is a turret with four TY90 series surface-to-air missiles (SAMs) mounted either side of the sensor package. The latter consists of a day/thermal sighting system and mounted above this is a new 3D radar, which can be folded down into the horizontal position for travelling.

According to NORINCO, the 3D radar has a detection range of 18 km and a tracking range of 10 km. Targets can be tracked either in the electro-optic mode or in the radar mode. The latter is especially useful when there is a threat of high electronic countermeasures.

Yitian features an automatic target tracking and engagement capability and can engage targets with a maximum velocity of up to 400 m/s.

Typical claimed reaction time is six to eight seconds. The Type TY90 missiles have a maximum effective range of 300 to 6,000 m with altitude coverage from 15 m up to 4,000 m. As eight missiles are carried multiple targets can be rapidly engaged.

Optional equipment includes an Identification Friend or Foe (IFF) capability. The system would typically be integrated on an overall C4 air-defence system, which could allocate targets to a particular weapon system.

Although Yitian is currently being marketed on a WZ 551 series 6 x 6 APC chassis, it can also be integrated onto other chassis, tracked and wheeled.

It has been confirmed that the WMZ 551B chassis is also used for a number of specialised versions including 105 mm low-recoil assault gun and 120 mm self-propelled mortar. Full details of both of these vehicles are given in a separate entry.

More specialised versions include an ambulance (WMZ 551JH) and command post vehicles with a raised roof for greater internal volume, recovery vehicle with a hydraulic crane mounted at the rear and rear-mounted spades (WMZ 551QJ) but there are a number of projected variants such as a specialised engineering vehicle.

Finally, there is a special forward observer version for use with artillery units and this is fitted with a roof-mounted sensor pod that contains day/night optronics and a laser range-finder. This is used to provide target information for artillery systems as well as surface-to-surface rocket systems. Mention has also been made of a version armed with a 100 mm gun.

This is based on the latest WMZ 551B chassis and is fitted with a turret armed with a 105 mm low-recoil gun that in addition to firing standard NATO types of tank ammunition can also fire a gun-launched guided projectile. It has been confirmed that this 105 mm assault gun version is now in service with the PLA.

The basic vehicle carrying 11 fully equipped troops plus a crew of two. It has a circular roof hatch and is armed with an externally mounted 12.7 mm machine gun for which 500 rounds are carried. Its empty weight is 12,500 kg, maximum payload on land 7,000 kg and maximum payload on water 3,500 kg.

This has a raised rear troop compartment, a crew of three and can carry four stretchers. Its empty weight is 12,600 kg. Mounted on the forward part of the roof is a cupola with an externally mounted 12.7 mm machine gun for which 500 rounds are carried.

This has the same turret as fitted to the full-tracked WZ 501 IFV described and illustrated in a separate entry and which in turn is a copy of the turret installed on the Russian BMP-1 vehicle. This is armed with a 73 mm gun (40 rounds carried), a coaxial 7.62 mm machine gun (2,000 rounds carried) and a NORINCO Red Arrow 73 ATGW mounted over the main armament, for which four missiles are carried. Combat weight is 14.2 tonnes.

This has a crew of two and is fitted with a one-man power-operated turret on the roof to the immediate rear of the engine compartment. To the rear of the turret are two rectangular roof hatches. The turret is also installed on the full-tracked YW 307 IFV.

This version is believed to have the designation of the WZ 551A or ZSL-92 in PLA service. There is also believed to be a WZ 551C.

This has also been referred to, at various times, as the Type 82, Type 90 and Type 92. It is now known to be in service with the PLA and took part in the parade held in Beijing late in 1999.

The turret can traverse through a full 360° and the 25 mm externally mounted cannon has an elevation of -8 to +55°. A 7.62 mm machine gun is mounted coaxial to the left of the 25 mm cannon and either side of the lower part of the turret are electrically operated smoke grenade dischargers. The gunner has a single-piece hatch cover that opens to the right, two day periscopes and a day/low-light level night sight which is mounted in the forward part of the turret roof.

The 25 mm cannon fires HE and API rounds and the gunner can select single shots or rates of fire of 100, 300 or 500 rds/min. Two hundred rounds of ready use 20 mm ammunition are carried plus a further 200 rounds in reserve. One thousand rounds of 7.62 mm ammunition are carried.

This is a WZ 551 with its turret removed and a hydraulic crane mounted on the rear of the vehicle. This has a telescopic jib and when not required is traversed to the front of the vehicle.

This is an 8 × 8 chassis fitted with a turret, armed with twin 23 mm cannon, it is understood that this never entered production or service.

This was shown for the first time in late 1988 and is essentially the NORINCO WZ 551 (6 × 6) vehicle fitted with the French Nexter Systems (previously Giat Industries) Dragar one-man power-operated turret. The Dragar turret weighs 1,250 kg and, in addition to being armed with the 25 mm Nexter Systems M811 cannon, is armed with a 7.62 mm machine gun and two banks of three electrically operated smoke grenade dischargers. As far as is known, this version of the WZ 551 has not entered production.

This is fitted with a one-man turret with four NORINCO Red Arrow 8 ATGWs ready to launch; an additional eight missiles are carried in reserve. The Red Arrow 8 missiles have a range of 100 to 3,000 m. The turret can be traversed through 360° and the launcher elevated from -7 to +13°. This version has a crew of four.

This version is known to have been produced in production quantities and in addition to being in service with the People's Liberation Army it is understood that a quantity has been obtained by the army of Bosnia-Herzegovina in the former Yugoslavia. The latter also has a quantity of the standard tripod-mounted infantry version of the Red Arrow 8.

As an alternative, the 4 × 4 version can be fitted with the one-man turret armed with the 73 mm gun, a 7.62 mm coaxial machine gun and the Red Arrow 73 ATGW.

The PLA is now using its well established NORINCO WZ 551 APC in a number of highly specialised reconnaissance roles.

A number of WZ 551 vehicles have been modified for the reconnaissance role and fitted with extensive communications equipment as well as a mast-mounted sensor pod.

This contains day/night observation equipment, laser range-finder and laser designator to provide a long-range surveillance and target acquisition capability under day and night conditions.

This sensor pod is mounted on a raised plinth situated on the roof of the vehicle but at this stage it is not known as to whether this can be raised in the vertical position for improved coverage.

Mounted to the rear of the sensor pod is a telescopic arm which retracts into the vehicle when not required and on top of this is a radar antenna.

Information obtained by these sensors is displayed on flat screens inside of the modified WZ 551 and can be relayed to the next chain of command in real time.

A battle management system is also understood to be integrated into this version of the WZ 551. An auxiliary power unit is installed to allow all of the onboard equipment to be run with the main diesel engine switched off. This version may lack any amphibious capability due to the increased weight of the installed equipment.

This variant has been referred to as a wheeled Reconnaissance Armoured Vehicle (RAV) and is normally issued to reconnaissance battalions.

During a recent exercise a WZ 551 fitted with extensive communications equipment was observed to be used to launch an ASN-15 mini unmanned aerial vehicle (UAV) to provide a real-time battlefield surveillance capability. This vehicle retained its full amphibious characteristics as well as the standard roof-mounted 12.7 mm heavy machine gun.

A similar 4 × 4 chassis is used for the latest NORINCO Red Arrow 9 heavy long-range anti-tank guided weapon system, which was shown for the first time in late 1999. This chassis is also referred to as the Type 92B and is covered in detail in a separate entry.

Available details of this system, which is fitted with what appears to be a modified Russian 2S23 NONA-SVK turret system, are given in a separate entry.

This system is fitted with a one-person turret armed with machine guns for use in the internal security role. Also referred to as the WZ 901 or Type 92B.

The chassis of the WZ 551 is used as the basis for the NORINCO PL-9 low-altitude surface-to-air missile system, which remains at the proposal stage. This system is also referred to as the WZ 551D air-defence vehicle and additional details are given in Jane's Land Based Air Defence.

This is based on a lengthened 6 × 6 chassis and mounted on the hull top at the rear is a turret armed with a 122 mm howitzer which has a maximum range of 15,000 to 21,000 m, depending on the type of ammunition used. The turret has a traverse of 25° left and right and the ordnance can be elevated from -3 to +70°. Forty rounds of ammunition are carried and, before firing commences, two spades can be lowered at the rear of the hull to provide a more stable firing platform. Available details of the NORINCO 122 mm (8 × 8) self-propelled artillery system are given in a separate entry. This remains at the prototype stage.

NORINCO is also suggesting that this vehicle could be fitted with the 73 mm turret or one with four 25 mm cannon for air defence use. As far as it is known, none of these 8 × 8 models have yet entered quantity production or service. Other variants

NORINCO has stated that other variants could include 82 mm and 120 mm self-propelled mortar systems. Ambulance and armoured command post vehicles have also been proposed by NORINCO.

Details of this new WMZ 551 (6×6) APC with a redesigned hull are given in a separate entry. The first prototype was completed in 2003. It should be noted that the new generation WZ 551 has been given the designation of the WMZ 551B. As of mid-2007 this had not been seen in public.